In an airplane turbojet, the combustion chamber is secured to the inside of a diffuser casing, upstream from the high-pressure turbine, by means of inner and outer fasteners, and together they form a combustion chamber module. The invention relates to the system of outer fasteners connecting said annular combustion chamber to the inside wall of the casing.
In the description below, the terms “upstream” and “downstream” are used to designate the positions of the elements of the structure relative to one another in the axial direction, taking the gas flow direction as the reference direction.
In the past, proposals have been made to connect the upstream end of the outer wall of the combustion chamber to the wall of the diffuser casing by means of a connection part that is annular and of relatively complex shape. The connection part is welded to the downstream end of the outer wall of the combustion chamber, and includes a flange at its own downstream end that is extended radially upstream and outwards by a conical portion. The conical portion is terminated by a radial annular plate that is bolted between a radial plate defined at the downstream end of the wall of the diffuser casing and another, similar plate of the turbine casing situated downstream from the diffuser casing.
Windows are formed through the conical portion in order to allow the air coming from the compressor to reach means for cooling the turbine. The above-described mount ensures that the combustion chamber is positioned and held inside the diffuser casing, while also allowing for relative displacements of thermal origin in order to limit stresses. Nevertheless, that technology is expensive, in particular because the connection part is complex in shape, and also because the contacting surfaces of the plates must be of excellent planeness, which requires expensive machining.